In any case, the possibility of multiple aboriginal cells does not survive into textbook neo-Darwinism, in which universal monophyly (a single Tree of Life, rooted in a common ancestor [cell]) is orthodoxy.

(If one argues, as do Vestigian et al. 2006 about the genetic code, that a biological character has come to be multiple times independently, that character cannot be used to establish monophyly, in this instance, the monophyly of life on Earth.)

However, a recent molecular analysis (Mueller et al. 2004) rejected the monophyly of ALL of these groups with the exception of Desmognathinae (but rather than being the sister-taxon to Plethodontinae it was nested within this group, and within it the sister-taxon to a ‘Hydromantes’-Aneides clade).